Fossilised pollen helps GNS scientists study climate change

Joe Prebble of GNS Science has used fossilised pollen to look at climate change over the last 34 million years.

Fossilised tree pollen is giving us a better understanding of climate change over the last 34 million years.

More than 2000 samples of fossilised tree pollen held at GNS Science in Lower Hutt have been looked at to get a picture of the climate over the past 34 million years, covering a period when New Zealand was six to eight degrees Celsius warmer than today.

The research, published this month in Earth and Planetary Science Letters, is based on fossilised tree pollen that scientists have extracted from rocks around New Zealand over the last 60 years.

By comparing the pollen found in the rocks to the modern distribution of closely-related trees, the scientists were able to reconstruct changes in air temperature and rainfall.

The scientists used pollen from about 75 plant species – mostly trees – and their distribution provides data on temperature and rainfall over the last 34 million years.

Some of the trees are today only found in New Caledonia, New Guinea and Australia.

The pollen grains are microscopic and generally need to be magnified several hundred times for meaningful study by scientists.

"Other than computer climate models, these types of fossil climate records are the only way we have to understand how climate responded to elevated carbon dioxide concentrations in the past, and might respond in the future," said palynologist Joe Prebble of GNS Science, the lead author of the study.